Effects of aqueous methanolic extract of Salvia limbata on antinociceptive activity and withdrawal syndrome in mice

Abstract

It is quite clear that the repeated use of opioid drugs leads to physical dependence and tolerance. Dependence can be measured by evaluation of self-restraint signs from abrupt drug withdrawal or administration of a narcotic antagonist or both. Effects of some Salvia genesis, of Salvia aerial parts extract on morphine dependence were investigated in mice. After induction of dependence by morphine, distilled water was injected into the control group and different concentrations of plants aerial extract were injected into the other five groups. To assess morphine withdrawal, mice were injected with naloxone (5 mg/kg) intraperitoneally (i.p.) on the 5th day. After four consecutive days of morphine injection, withdrawal syndrome was assessed by placing each mouse in a 30 cm high glass box and recording the incidence of escape jumps for 60 min. Animal receiving acute treatment with morphine displayed dependence. The animals treated with different Salvia limbata aerial (flowered browse) parts extracts concentration decreased incidence of escape jumps in number or decreased development of morphine dependence and on the other hand, addiction was observed following naloxone administration (P<0.001). Results from the present study showed that the methanolic extract from aerial parts of Salvia limbata produced a statistically significant inhibition of pain induced by hot plate latency at (500, 1000 and 1500 mg/kg) i.p. dose, as compared to the control groups. A significant increase in pain threshold after 30 and 60 min of i.p. injection of extract, compared with the control groups (P<0.001). The activity was comparable to that of morphine (30 mg kg-1 i.p., p> 0.05). The anti-nociceptive activity of S. limbata increased until the 60th min as compared to morphine (P<0.05).

Key words: Morphine dependence, anti-nociceptive activity, Salvia limbata, jumping, hot plate method.